Cold snap not enough to zap beetle threat

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DENVER — Experts say Colorado’s plunge into a deep freeze is too little and too late to disrupt the population of the destructive pine beetle.

Dave Leatherman, a retired Colorado State Forest Service entomologist, told The Denver Post that long periods of extreme cold can cut down the pine beetle population, but the pests have already burrowed themselves deep into the trees to protect themselves.

Plus, “they’ve already changed their chemical physiology and increased the percentage of glycols in their systems. It’s the main component of anti-freeze we put in our cars,” said Leatherman, who worked for the Forest Service from 1974 to 2005.

Overnight lows in some mountainous areas have dropped to minus 20 degrees for consecutive days, but temperatures would have to drop to minus 30 or lower and stay there for at least five to seven days to affect pine beetle populations between December and February.

“Although it’s been really cold and long lasting, I don’t think it’s what we would consider cold enough and long enough,” Leatherman said, adding that had the extreme cold hit in October or November, it could have had an effect. The current beetle infestation has claimed about 6.6 million acres of lodgepole pine forests in the state, according to the state Forest Service.

Prolonged drought and warmer weather have weakened Colorado forests, allowing the pine beetle to be even more destructive. But the infestation is on the decline in the state, primarily because the beetle has already feasted on most of the prime lodgepole pine in the northern mountains.

“Essentially, they’ve eaten themselves out of house and home,” Leatherman said.

Now foresters fear the beetle will spread into ponderosa pine stands, which grow primarily at lower elevations than lodgepole.